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kcsan: Show full access type in report

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This commit adds access-type information to KCSAN's reports as follows:
"read", "read (marked)", "write", and "write (marked)".

Suggested-by: Paul E. McKenney <paulmck@kernel.org>
Signed-off-by: Marco Elver <elver@google.com>
Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
This commit is contained in:
Marco Elver 2020-01-10 19:48:33 +01:00 committed by Ingo Molnar
parent 5c36142574
commit 47144eca28
3 changed files with 37 additions and 23 deletions
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15
kernel/kcsan/core.c
View file

@ -255,7 +255,7 @@ static inline unsigned int get_delay(void)
static noinline void kcsan_found_watchpoint(const volatile void *ptr, static noinline void kcsan_found_watchpoint(const volatile void *ptr,
size_t size, size_t size,
bool is_write, int type,
atomic_long_t *watchpoint, atomic_long_t *watchpoint,
long encoded_watchpoint) long encoded_watchpoint)
{ {
@ -276,7 +276,7 @@ static noinline void kcsan_found_watchpoint(const volatile void *ptr,
flags = user_access_save(); flags = user_access_save();
if (consumed) { if (consumed) {
kcsan_report(ptr, size, is_write, true, raw_smp_processor_id(), kcsan_report(ptr, size, type, true, raw_smp_processor_id(),
KCSAN_REPORT_CONSUMED_WATCHPOINT); KCSAN_REPORT_CONSUMED_WATCHPOINT);
} else { } else {
/* /*
@ -292,8 +292,9 @@ static noinline void kcsan_found_watchpoint(const volatile void *ptr,
} }
static noinline void static noinline void
kcsan_setup_watchpoint(const volatile void *ptr, size_t size, bool is_write) kcsan_setup_watchpoint(const volatile void *ptr, size_t size, int type)
{ {
const bool is_write = (type & KCSAN_ACCESS_WRITE) != 0;
atomic_long_t *watchpoint; atomic_long_t *watchpoint;
union { union {
u8 _1; u8 _1;
@ -415,13 +416,13 @@ kcsan_setup_watchpoint(const volatile void *ptr, size_t size, bool is_write)
* No need to increment 'data_races' counter, as the racing * No need to increment 'data_races' counter, as the racing
* thread already did. * thread already did.
*/ */
kcsan_report(ptr, size, is_write, size > 8 || value_change, kcsan_report(ptr, size, type, size > 8 || value_change,
smp_processor_id(), KCSAN_REPORT_RACE_SIGNAL); smp_processor_id(), KCSAN_REPORT_RACE_SIGNAL);
} else if (value_change) { } else if (value_change) {
/* Inferring a race, since the value should not have changed. */ /* Inferring a race, since the value should not have changed. */
kcsan_counter_inc(KCSAN_COUNTER_RACES_UNKNOWN_ORIGIN); kcsan_counter_inc(KCSAN_COUNTER_RACES_UNKNOWN_ORIGIN);
if (IS_ENABLED(CONFIG_KCSAN_REPORT_RACE_UNKNOWN_ORIGIN)) if (IS_ENABLED(CONFIG_KCSAN_REPORT_RACE_UNKNOWN_ORIGIN))
kcsan_report(ptr, size, is_write, true, kcsan_report(ptr, size, type, true,
smp_processor_id(), smp_processor_id(),
KCSAN_REPORT_RACE_UNKNOWN_ORIGIN); KCSAN_REPORT_RACE_UNKNOWN_ORIGIN);
} }
@ -455,10 +456,10 @@ static __always_inline void check_access(const volatile void *ptr, size_t size,
*/ */
if (unlikely(watchpoint != NULL)) if (unlikely(watchpoint != NULL))
kcsan_found_watchpoint(ptr, size, is_write, watchpoint, kcsan_found_watchpoint(ptr, size, type, watchpoint,
encoded_watchpoint); encoded_watchpoint);
else if (unlikely(should_watch(ptr, type))) else if (unlikely(should_watch(ptr, type)))
kcsan_setup_watchpoint(ptr, size, is_write); kcsan_setup_watchpoint(ptr, size, type);
} }
/* === Public interface ===================================================== */ /* === Public interface ===================================================== */

2
kernel/kcsan/kcsan.h
View file

@ -103,7 +103,7 @@ enum kcsan_report_type {
/* /*
* Print a race report from thread that encountered the race. * Print a race report from thread that encountered the race.
*/ */
extern void kcsan_report(const volatile void *ptr, size_t size, bool is_write, extern void kcsan_report(const volatile void *ptr, size_t size, int access_type,
bool value_change, int cpu_id, enum kcsan_report_type type); bool value_change, int cpu_id, enum kcsan_report_type type);
#endif /* _KERNEL_KCSAN_KCSAN_H */ #endif /* _KERNEL_KCSAN_KCSAN_H */

43
kernel/kcsan/report.c
View file

@ -24,7 +24,7 @@
static struct { static struct {
const volatile void *ptr; const volatile void *ptr;
size_t size; size_t size;
bool is_write; int access_type;
int task_pid; int task_pid;
int cpu_id; int cpu_id;
unsigned long stack_entries[NUM_STACK_ENTRIES]; unsigned long stack_entries[NUM_STACK_ENTRIES];
@ -41,8 +41,10 @@ static DEFINE_SPINLOCK(report_lock);
* Special rules to skip reporting. * Special rules to skip reporting.
*/ */
static bool static bool
skip_report(bool is_write, bool value_change, unsigned long top_frame) skip_report(int access_type, bool value_change, unsigned long top_frame)
{ {
const bool is_write = (access_type & KCSAN_ACCESS_WRITE) != 0;
if (IS_ENABLED(CONFIG_KCSAN_REPORT_VALUE_CHANGE_ONLY) && is_write && if (IS_ENABLED(CONFIG_KCSAN_REPORT_VALUE_CHANGE_ONLY) && is_write &&
!value_change) { !value_change) {
/* /*
@ -63,9 +65,20 @@ skip_report(bool is_write, bool value_change, unsigned long top_frame)
return kcsan_skip_report_debugfs(top_frame); return kcsan_skip_report_debugfs(top_frame);
} }
static inline const char *get_access_type(bool is_write) static const char *get_access_type(int type)
{ {
return is_write ? "write" : "read"; switch (type) {
case 0:
return "read";
case KCSAN_ACCESS_ATOMIC:
return "read (marked)";
case KCSAN_ACCESS_WRITE:
return "write";
case KCSAN_ACCESS_WRITE | KCSAN_ACCESS_ATOMIC:
return "write (marked)";
default:
BUG();
}
} }
/* Return thread description: in task or interrupt. */ /* Return thread description: in task or interrupt. */
@ -112,7 +125,7 @@ static int sym_strcmp(void *addr1, void *addr2)
/* /*
* Returns true if a report was generated, false otherwise. * Returns true if a report was generated, false otherwise.
*/ */
static bool print_report(const volatile void *ptr, size_t size, bool is_write, static bool print_report(const volatile void *ptr, size_t size, int access_type,
bool value_change, int cpu_id, bool value_change, int cpu_id,
enum kcsan_report_type type) enum kcsan_report_type type)
{ {
@ -124,7 +137,7 @@ static bool print_report(const volatile void *ptr, size_t size, bool is_write,
/* /*
* Must check report filter rules before starting to print. * Must check report filter rules before starting to print.
*/ */
if (skip_report(is_write, true, stack_entries[skipnr])) if (skip_report(access_type, true, stack_entries[skipnr]))
return false; return false;
if (type == KCSAN_REPORT_RACE_SIGNAL) { if (type == KCSAN_REPORT_RACE_SIGNAL) {
@ -132,7 +145,7 @@ static bool print_report(const volatile void *ptr, size_t size, bool is_write,
other_info.num_stack_entries); other_info.num_stack_entries);
/* @value_change is only known for the other thread */ /* @value_change is only known for the other thread */
if (skip_report(other_info.is_write, value_change, if (skip_report(other_info.access_type, value_change,
other_info.stack_entries[other_skipnr])) other_info.stack_entries[other_skipnr]))
return false; return false;
} }
@ -170,7 +183,7 @@ static bool print_report(const volatile void *ptr, size_t size, bool is_write,
switch (type) { switch (type) {
case KCSAN_REPORT_RACE_SIGNAL: case KCSAN_REPORT_RACE_SIGNAL:
pr_err("%s to 0x%px of %zu bytes by %s on cpu %i:\n", pr_err("%s to 0x%px of %zu bytes by %s on cpu %i:\n",
get_access_type(other_info.is_write), other_info.ptr, get_access_type(other_info.access_type), other_info.ptr,
other_info.size, get_thread_desc(other_info.task_pid), other_info.size, get_thread_desc(other_info.task_pid),
other_info.cpu_id); other_info.cpu_id);
@ -181,14 +194,14 @@ static bool print_report(const volatile void *ptr, size_t size, bool is_write,
pr_err("\n"); pr_err("\n");
pr_err("%s to 0x%px of %zu bytes by %s on cpu %i:\n", pr_err("%s to 0x%px of %zu bytes by %s on cpu %i:\n",
get_access_type(is_write), ptr, size, get_access_type(access_type), ptr, size,
get_thread_desc(in_task() ? task_pid_nr(current) : -1), get_thread_desc(in_task() ? task_pid_nr(current) : -1),
cpu_id); cpu_id);
break; break;
case KCSAN_REPORT_RACE_UNKNOWN_ORIGIN: case KCSAN_REPORT_RACE_UNKNOWN_ORIGIN:
pr_err("race at unknown origin, with %s to 0x%px of %zu bytes by %s on cpu %i:\n", pr_err("race at unknown origin, with %s to 0x%px of %zu bytes by %s on cpu %i:\n",
get_access_type(is_write), ptr, size, get_access_type(access_type), ptr, size,
get_thread_desc(in_task() ? task_pid_nr(current) : -1), get_thread_desc(in_task() ? task_pid_nr(current) : -1),
cpu_id); cpu_id);
break; break;
@ -223,7 +236,7 @@ static void release_report(unsigned long *flags, enum kcsan_report_type type)
* required for the report type, simply acquires report_lock and returns true. * required for the report type, simply acquires report_lock and returns true.
*/ */
static bool prepare_report(unsigned long *flags, const volatile void *ptr, static bool prepare_report(unsigned long *flags, const volatile void *ptr,
size_t size, bool is_write, int cpu_id, size_t size, int access_type, int cpu_id,
enum kcsan_report_type type) enum kcsan_report_type type)
{ {
if (type != KCSAN_REPORT_CONSUMED_WATCHPOINT && if (type != KCSAN_REPORT_CONSUMED_WATCHPOINT &&
@ -243,7 +256,7 @@ static bool prepare_report(unsigned long *flags, const volatile void *ptr,
other_info.ptr = ptr; other_info.ptr = ptr;
other_info.size = size; other_info.size = size;
other_info.is_write = is_write; other_info.access_type = access_type;
other_info.task_pid = in_task() ? task_pid_nr(current) : -1; other_info.task_pid = in_task() ? task_pid_nr(current) : -1;
other_info.cpu_id = cpu_id; other_info.cpu_id = cpu_id;
other_info.num_stack_entries = stack_trace_save(other_info.stack_entries, NUM_STACK_ENTRIES, 1); other_info.num_stack_entries = stack_trace_save(other_info.stack_entries, NUM_STACK_ENTRIES, 1);
@ -302,14 +315,14 @@ static bool prepare_report(unsigned long *flags, const volatile void *ptr,
goto retry; goto retry;
} }
void kcsan_report(const volatile void *ptr, size_t size, bool is_write, void kcsan_report(const volatile void *ptr, size_t size, int access_type,
bool value_change, int cpu_id, enum kcsan_report_type type) bool value_change, int cpu_id, enum kcsan_report_type type)
{ {
unsigned long flags = 0; unsigned long flags = 0;
kcsan_disable_current(); kcsan_disable_current();
if (prepare_report(&flags, ptr, size, is_write, cpu_id, type)) { if (prepare_report(&flags, ptr, size, access_type, cpu_id, type)) {
if (print_report(ptr, size, is_write, value_change, cpu_id, type) && panic_on_warn) if (print_report(ptr, size, access_type, value_change, cpu_id, type) && panic_on_warn)
panic("panic_on_warn set ...\n"); panic("panic_on_warn set ...\n");
release_report(&flags, type); release_report(&flags, type);